1. Field of Invention
The embodiments of the present invention generally relate to a transfer chamber utilized in semiconductor fabrication systems.
2. Background of Invention
Semiconductor substrate processing is typically performed by subjecting a substrate to a plurality of sequential processes to create devices, conductors and insulators on the substrate. These processes are generally performed in a process chamber configured to perform a single step of the production process. In order to efficiently complete the entire sequence of processing steps, a number of process chambers are typically coupled to a central transfer chamber that houses a robot to facilitate transfer of the substrate between the surrounding process chambers. A semiconductor processing platform having this configuration is generally known as a cluster tool, examples of which are the families of CENTURA(copyright) and ENDURA(copyright) processing platforms available from Applied Materials, Inc., of Santa Clara, Calif.
Generally, a cluster tool consists of a central transfer chamber having a robot disposed therein. The transfer chamber is generally surrounded by one of more process chambers and at least one load lock chamber to facilitate transfer of substrates into and out of the tool. The process chambers are generally utilized to process the substrate, for example, performing various processing steps such as etching, physical vapor deposition, chemical vapor deposition, ion implantation, lithography and the like. As the processes performed in the process chambers are generally performed at vacuum pressure, the transfer chamber is maintained at vacuum pressure as well to eliminate having to repeatedly pump down the process chamber after each substrate transfer.
Vacuum is established and maintained in the transfer chamber utilizing a pumping system coupled thereto. Typically, the pumping system is coupled to the transfer chamber via a pumping port that is disposed in the bottom of the transfer chamber. The pumping port is centrally located in the chamber bottom to enhance the conductance of the chamber. Good conductance allows for smaller pumping components and faster chamber pump down times.
However, having the pumping port disposed in the chamber bottom often allows intake into the pumping system of contaminants such as particles and substrate fragments that accumulate on the chamber bottom. These particles and other contaminants reduce the performance and service life of the pumping components.
One solution that has been employed to minimize particle intake is to utilize a tubular extension fastened over the port to elevate the port""s intake above the chamber bottom. The tubular extension, while not significantly effecting pumping conductance adversely, creates an obstacle that must be avoided by the robots moving within the chamber. Moreover, vibration produced by the pumping components and other chamber devices cause particles to be generated at the extension/chamber interface. These particles also adversely affect the pump""s performance and service life, thereby not totally resolving the increased maintenance interval required to maintain the pump""s efficiency due to particle exposure.
Another problem encountered in transfer chambers is damage to sensors and probes disposed therein. For example, ion probes such as those employed to monitor the ion energy and ion density within the transfer chamber. Ion probes typically include an exposed filament that is easily damaged upon contact. During routine chamber maintenance to remove particulates and other contamination from the interior of the chamber, the probe""s filament, which is disposed or positioned adjacent to the wiped areas, is susceptible to damage by the technicians. Accidental contact of the probe by the technicians during the wipe-down may damage the filament, rendering the probe inoperable, necessitating the opening of the transfer chamber to replace the probe and further cleaning of the chamber.
Moreover, sensors utilized in the transfer chamber are commonly positioned in or near ports disposed on the chamber bottom. Particulates that accumulate on the chamber bottom may enter the port having the sensor disposed therein. Additionally, gas ports positioned on the chamber bottom adjacent the sensor port may blow particles into the sensor port. The particles entering the sensor port may contaminate the sensor and adversely affect sensor accuracy.
Therefore, there is a need for an improved port in a transfer chamber for both sensor shielding and pumping applications.
One aspect of the invention generally provides a chamber for transferring a substrate. In one embodiment, a chamber for transferring a substrate is provided that includes at least one side wall coupled to a chamber bottom and supporting a lid that define an evacuable volume therebetween. A passage is disposed through the side wall and chamber bottom. The passage has a first end that is disposed in the side wall and is exposed to the evacuable volume. The passage has a second end that is disposed on an exterior side of the chamber bottom. The system may further comprise a pumping system that is coupled to the second end of the passage. The passage enhances pumping conductance while protecting pumping system components elevating the first end from the chamber bottom.
In another aspect of the invention, a chamber for transferring a substrate is provided that includes at least one side wall coupled to a chamber bottom defining an evacuable volume therebetween. A passage having a first portion and a second portion is disposed through the side wall and chamber bottom. The first portion of the passage is exposed to the evacuable volume. The second portion of the passage is coupled obliquely to the first portion and has a sensor disposed therein. As the probe""s position in the second portion of the passage shields the probe from the interior volume of the chamber, the probe is protected from incidental contact and possible damage by activities within the transfer chamber.